<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On May 20, 2019, at 2:03 PM, Ben Craig <<a href="mailto:ben.craig@ni.com" class="">ben.craig@ni.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I guess it depends if the goal is to have a spin lock class, or a sharded lock table.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">If it’s a spin lock class, then someone needs to just make the class and get it into some header and/or static lib somewhere. The specifics aren’t super important.</div></div></div></blockquote><div><br class=""></div><div>The former.</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">If it’s a sharded lock table, then you need to figure out which dynamic library will provide it, and how that will interact with libc++ when it is used atop libsupc++ or built with GCC.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="border-style: none none none solid; border-left-width: 1.5pt; border-left-color: blue; padding: 0in 0in 0in 4pt;" class=""><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span><a href="mailto:jfbastien@apple.com" class="">jfbastien@apple.com</a> <<a href="mailto:jfbastien@apple.com" class="">jfbastien@apple.com</a>><span class="Apple-converted-space"> </span><br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Monday, May 20, 2019 3:59 PM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span>Mitch Phillips <<a href="mailto:mitchphillips@outlook.com" class="">mitchphillips@outlook.com</a>><br class=""><b class="">Cc:</b><span class="Apple-converted-space"> </span>Ben Craig <<a href="mailto:ben.craig@ni.com" class="">ben.craig@ni.com</a>>; Olivier Giroux <<a href="mailto:OGiroux@nvidia.com" class="">OGiroux@nvidia.com</a>>; <a href="mailto:libcxx-dev@lists.llvm.org" class="">libcxx-dev@lists.llvm.org</a>; <a href="mailto:kostyak@google.com" class="">kostyak@google.com</a><br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>[EXTERNAL] Re: [libcxx-dev] Is a compiler-rt shared spinlock implementation of any use to libcxx?<o:p class=""></o:p></div></div></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">“Freestanding” is meant for a few things, of which: codebases that can’t have external dependencies, “bare metal” code or other embedded code. This sounds exactly like what you’re after.<o:p class=""></o:p></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">The projects are all in the same repository. You can absolutely depend on having it: it’s in the same repo. You therefore don’t need to duplicate anything.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><br class=""><br class=""><o:p class=""></o:p></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On May 20, 2019, at 1:55 PM, Mitch Phillips <<a href="mailto:mitchphillips@outlook.com" style="color: purple; text-decoration: underline;" class="">mitchphillips@outlook.com</a>> wrote:<o:p class=""></o:p></div></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I'm a little confused about how said aformentioned freestanding implementation would work. We (GWP-ASan + Scudo) can't depend on having libcxx (we actually<span class="Apple-converted-space"> </span><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D62048&d=DwMFaQ&c=I_0YwoKy7z5LMTVdyO6YCiE2uzI1jjZZuIPelcSjixA&r=y8mub81SfUi-UCZRX0Vl1g&m=0JDRKupnKG2FyAYi69CfJqswn5ys3q3D8nrjL8eqtQw&s=AgRXbJ1EHKQtYIn_0Ku-RB1v_LizN2Q4nVeZ595pZa8&e=" style="color: purple; text-decoration: underline;" class="">explicitly disable</a><span class="Apple-converted-space"> </span>using of the c++ standard library for these libraries), and I don't know where we could have a shared implementation live (that could be used by both us and libcxx).<o:p class=""></o:p></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Would we have a spinlock implementation in libcxx and have that guarded by a macro definition before the include of <mutex>, and then keep a synchronised version in compiler-rt?<o:p class=""></o:p></div></div></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On Mon, May 20, 2019 at 10:10 AM Ben Craig <<a href="mailto:ben.craig@ni.com" style="color: purple; text-decoration: underline;" class="">ben.craig@ni.com</a>> wrote:<o:p class=""></o:p></div></div><blockquote style="border-style: none none none solid; border-left-width: 1pt; border-left-color: rgb(204, 204, 204); padding: 0in 0in 0in 6pt; margin-left: 4.8pt; margin-right: 0in;" class=""><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Wouldn’t all the Scudo and sanitizer things count as part of the toolchain implementation though? Having pieces of the toolchain use an alternative name seems pretty reasonable to me.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">If the goal is to have a freestanding std::mutex that is implemented as a spin lock, well, that’s different. I could be convinced that’s a good thing to have, but I’m still a bit uneasy about it.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="border-style: none none none solid; border-left-width: 1.5pt; border-left-color: blue; padding: 0in 0in 0in 4pt;" class=""><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span><a href="mailto:jfbastien@apple.com" target="_blank" style="color: purple; text-decoration: underline;" class="">jfbastien@apple.com</a><span class="Apple-converted-space"> </span><<a href="mailto:jfbastien@apple.com" target="_blank" style="color: purple; text-decoration: underline;" class="">jfbastien@apple.com</a>><span class="Apple-converted-space"> </span><br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Monday, May 20, 2019 11:27 AM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span>Ben Craig <<a href="mailto:ben.craig@ni.com" target="_blank" style="color: purple; text-decoration: underline;" class="">ben.craig@ni.com</a>><br class=""><b class="">Cc:</b><span class="Apple-converted-space"> </span>Olivier Giroux <<a href="mailto:OGiroux@nvidia.com" target="_blank" style="color: purple; text-decoration: underline;" class="">OGiroux@nvidia.com</a>>; Mitch Phillips <<a href="mailto:mitchphillips@outlook.com" target="_blank" style="color: purple; text-decoration: underline;" class="">mitchphillips@outlook.com</a>>;<span class="Apple-converted-space"> </span><a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class="">libcxx-dev@lists.llvm.org</a>;<a href="mailto:kostyak@google.com" target="_blank" style="color: purple; text-decoration: underline;" class="">kostyak@google.com</a><br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>[EXTERNAL] Re: [libcxx-dev] Is a compiler-rt shared spinlock implementation of any use to libcxx?<o:p class=""></o:p></div></div></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I think what developers *use* should definitely be named std::mutex. We indeed want to consider how the ABI is exposed, that’s a good question for libc++ maintainers.<o:p class=""></o:p></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div class=""><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p class=""> </o:p></p><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On May 20, 2019, at 6:23 AM, Ben Craig <<a href="mailto:ben.craig@ni.com" target="_blank" style="color: purple; text-decoration: underline;" class="">ben.craig@ni.com</a>> wrote:<o:p class=""></o:p></div></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I think it’s fine to give such a class the same interface as std::mutex, just please don’t actually name it std::mutex. I would be pretty concerned about ABI compatibility in that situation, as well as subtle interactions with things like condition_variable::wait. cxxabi::__mutex, or almost any other identifier would be fine.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div style="border-style: none none none solid; border-left-width: 1.5pt; border-left-color: blue; padding: 0in 0in 0in 4pt;" class=""><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="gmail-m-1501418984181503871apple-converted-space"> </span>libcxx-dev <<a href="mailto:libcxx-dev-bounces@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class="">libcxx-dev-bounces@lists.llvm.org</a>><span class="gmail-m-1501418984181503871apple-converted-space"> </span><b class="">On Behalf Of<span class="gmail-m-1501418984181503871apple-converted-space"> </span></b>Olivier Giroux via libcxx-dev<br class=""><b class="">Sent:</b><span class="gmail-m-1501418984181503871apple-converted-space"> </span>Friday, May 17, 2019 7:55 PM<br class=""><b class="">To:</b><span class="gmail-m-1501418984181503871apple-converted-space"> </span>JF Bastien <<a href="mailto:jfbastien@apple.com" target="_blank" style="color: purple; text-decoration: underline;" class="">jfbastien@apple.com</a>>; Mitch Phillips <<a href="mailto:mitchphillips@outlook.com" target="_blank" style="color: purple; text-decoration: underline;" class="">mitchphillips@outlook.com</a>><br class=""><b class="">Cc:</b><span class="gmail-m-1501418984181503871apple-converted-space"> </span><a href="mailto:kostyak@google.com" target="_blank" style="color: purple; text-decoration: underline;" class="">kostyak@google.com</a>;<span class="Apple-converted-space"> </span><a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class="">libcxx-dev@lists.llvm.org</a><br class=""><b class="">Subject:</b><span class="gmail-m-1501418984181503871apple-converted-space"> </span>[EXTERNAL] Re: [libcxx-dev] Is a compiler-rt shared spinlock implementation of any use to libcxx?<o:p class=""></o:p></div></div></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">That’s what makes the most sense to me, include <mutex> with a macro that freestanding would also use. Inside of that, I would have an implementation of standard mutex backed by atomics and the atomic_wait/atomic_notify_* functions, themselves configured with a macro to not rely on the OS in freestanding implementations.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Olivier<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(181, 196, 223); padding: 3pt 0in 0in;" class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-size: 12pt;" class="">From:<span class="gmail-m-1501418984181503871apple-converted-space"> </span></span></b><span style="font-size: 12pt;" class="">libcxx-dev <<a href="mailto:libcxx-dev-bounces@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">libcxx-dev-bounces@lists.llvm.org</span></a>> on behalf of JF Bastien via libcxx-dev <<a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">libcxx-dev@lists.llvm.org</span></a>><br class=""><b class="">Reply-To:<span class="gmail-m-1501418984181503871apple-converted-space"> </span></b>JF Bastien <<a href="mailto:jfbastien@apple.com" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">jfbastien@apple.com</span></a>><br class=""><b class="">Date:<span class="gmail-m-1501418984181503871apple-converted-space"> </span></b>Friday, May 17, 2019 at 4:40 PM<br class=""><b class="">To:<span class="gmail-m-1501418984181503871apple-converted-space"> </span></b>Mitch Phillips <<a href="mailto:mitchphillips@outlook.com" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">mitchphillips@outlook.com</span></a>><br class=""><b class="">Cc:<span class="gmail-m-1501418984181503871apple-converted-space"> </span></b>"<a href="mailto:kostyak@google.com" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">kostyak@google.com</span></a>" <<a href="mailto:kostyak@google.com" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">kostyak@google.com</span></a>>, "<a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">libcxx-dev@lists.llvm.org</span></a>" <<a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">libcxx-dev@lists.llvm.org</span></a>><br class=""><b class="">Subject:<span class="gmail-m-1501418984181503871apple-converted-space"> </span></b>Re: [libcxx-dev] Is a compiler-rt shared spinlock implementation of any use to libcxx?</span><o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I think it makes sense for libc++ to have a version of mutex which has the same API as the standard one, but for “freestanding” platforms such as yours. A flavor which mostly just spins and yields as in your review.<o:p class=""></o:p></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I’m not sure how to best turn it on, though. Should it be controlled by a macro, and otherwise it just looks like you’re using <mutex>?<o:p class=""></o:p></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 11pt; font-family: Calibri, sans-serif;"> <o:p class=""></o:p></p><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On May 17, 2019, at 1:49 PM, Mitch Phillips via libcxx-dev <<a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">libcxx-dev@lists.llvm.org</span></a>> wrote:<o:p class=""></o:p></div></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Hi all,<span class="gmail-m-1501418984181503871apple-converted-space"> </span><o:p class=""></o:p></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">In a recent<span class="gmail-m-1501418984181503871apple-converted-space"> </span><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D61923-231503272&d=DwMGaQ&c=I_0YwoKy7z5LMTVdyO6YCiE2uzI1jjZZuIPelcSjixA&r=y8mub81SfUi-UCZRX0Vl1g&m=yw9dJtPZSvMNi00nrRSUlnN4NTQzKvXzHbd5w8ShH8A&s=uW10gtroz30NxGIUU3BvNH5efGnzv2tds3P49eY5ri4&e=" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">discussion</span></a><span class="gmail-m-1501418984181503871apple-converted-space"> </span>from the reviews of<span class="gmail-m-1501418984181503871apple-converted-space"> </span><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D60593&d=DwMGaQ&c=I_0YwoKy7z5LMTVdyO6YCiE2uzI1jjZZuIPelcSjixA&r=y8mub81SfUi-UCZRX0Vl1g&m=yw9dJtPZSvMNi00nrRSUlnN4NTQzKvXzHbd5w8ShH8A&s=rKVj5vHVGEsEZRjMkiN2X6e0bAfdTY7iVW0laX2AO8o&e=" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">GWP-ASan</span></a>, it was mentioned that I should probably consult with cxx-dev to see whether they'd be interested in a common spinlock implementation.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">The problem is:<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> - Scudo hardened allocator (compiler-rt/lib/scudo) requires its own spinlock as it can't use the C++ standard library due to Fuchsia requirements.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> - GWP-ASan (as it's packaged into Scudo) also requires a spinlock.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> - Compiler-rt sanitizer_common also can't use c++ stdlib, and has its own spinlock. We can't reuse the sanitizer_common spinlock for Scudo/GWP-ASan as it's currently tightly coupled into sanitizer_common, and Scudo+Fuchsia can't afford the code size overhead of pulling the entire sanitizer_common library.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">The plan was to basically write a small standalone spinlock implementation that can be used by all three of these requirements. Would libcxx benefit by us making this an llvm-common spinlock rather than compiler-rt-common? If so, are there any requirements that we need to be aware of?<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Cheers,<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Mitch.<o:p class=""></o:p></div></div></div></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">_______________________________________________<br class="">libcxx-dev mailing list<br class=""><a href="mailto:libcxx-dev@lists.llvm.org" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">libcxx-dev@lists.llvm.org</span></a><br class=""><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_libcxx-2Ddev&d=DwQGaQ&c=I_0YwoKy7z5LMTVdyO6YCiE2uzI1jjZZuIPelcSjixA&r=y8mub81SfUi-UCZRX0Vl1g&m=yw9dJtPZSvMNi00nrRSUlnN4NTQzKvXzHbd5w8ShH8A&s=SLhw06SYT_9fwfHOjm_nzQZ0LuPvmMe_b2gjd-VEFcc&e=" target="_blank" style="color: purple; text-decoration: underline;" class=""><span style="color: purple;" class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/libcxx-dev</span></a><o:p class=""></o:p></div></div></div></blockquote></div><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div></div><div class=""><div class="MsoNormal" align="center" style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-align: center;"><hr size="2" width="100%" align="center" class=""></div></div><div class=""><div class=""><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">This email message is for the sole use of the intended recipient(s) and may contain confidential information. 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